As shown in FIG. 1, rocker type conduit benders operate by hydraulic ram force F transmitted through pivot axis A on the shoe 1. This action causes the shoe to revolve around or near axis B which is the centerline location of the shoe radius R. The conduit C is bent between shoe 1 and follow bar 2 which slides on roller 3 as the shoe revolves. A saddle 4 fixed on the shoe grips the conduit for bending.
As is apparent, the lever arm L between axes or points A and B varies in magnitude as the hydraulic ram 6 moves connector pin 7 (forming pivot axis A) along slots 8 in the connector bars 9 in the direction of the roller 3. As a result of the geometrical variation between axes A and B and hence in the length of the lever arm as the shoe rotates, a large variation in bending force exerted on the conduit C exists and in the past has produced non-uniform bends in larger conduit sizes.